Nanometer-scale Distributions of Field Emission Current Measured with Scanning Tunneling Microscopy

Nanometer-scale distributions of field emission current and local work function are compared on two contrasting systems. In the case of the graphene adsorbed on Pt(111) where the electronic structure is spatially perturbed, the electron emission current is higher at the sites with lower work functions. On the other hand, in the case of Ar ion-bombarded HfC thin films, the electron emission current is higher at the geometrically lower and defective grain boundaries with higher work functions. The obtained results suggest that field emission is not necessarily determined only by the work function and geometrical features.